Hi Tanya,
I've been checking into this more and more. What you're saying is quite correct, in that the vaccine isn't 100%. But it would be the best chance of protection. The problem is, that Chicken Pox, while a harmless disease for children, becomes increasing dangerous as we age. The older you get, the worse it can be. In your sisters case, she is either very lucky, or may have had them very young without knowing it, and therefore has immunity.
Shingles is another example. I can speak from experience here. I had them in my late 30's. I had no idea what was going on. Wasn't too bad for me really, very fluish plus the welts/rash. The Dr. said that the older you become the worse it is. Someone in their 80's could die from it.
Our GI still hasn't called back with a plan for my daughter. I think she's still confering. She really has alot of confidence in the Imuran route, but may be past the most opportune time for using it.
How are things since you resection?
Tom.